U.S. Pat. No. 7,495,719B2 (Adachi et al.; 24 Feb. 2009) describes a display device capable of being electrically switchable between a state that displays a high-quality image (normal mode) and a mirror mode. The mirror mode produces an easy-to-view reflection image suitable for a person to view his/her own face or figure. With reference to FIG. 1 of Adachi (also included as FIG. 1 herein), the display device has an image display portion 1000, a reflective polarization selection member 300, a transmission polarization axis variable portion 400, and an absorbing polarization selection member 500, which are successively disposed. The image display portion 1000 includes an absorbing polarization selection member 208 that transmits a linear polarization component of a predetermined direction and absorbs a linear polarization component of a direction orthogonal thereto, and the absorbing polarization selection member 208 is disposed at the reflective polarization selection member 300 side.
U.S. Pat. No. 5,686,979 (Weber et al.; 11 Nov. 2011) describes the use of a standard backlight, a reflective polariser film (DBEF), a first simple switchable liquid crystal panel and a second liquid crystal display (LCD) capable of showing images. These components are assembled to yield a display system that can be switched between a transmissive display mode that utilises the backlight and a reflective display mode that does not use the backlight. A reflective LCD is particularly useful for viewing images in high ambient lighting conditions. U.S. Pat. No. 5,686,979 also describes the use of reflective polariser films (DBEF) and a single image display to yield a display system capable of conveying text and monochrome pictures.
WO2014002402A1 (Smith et al.; 3 Jan. 2014) describes the use of reflective polariser films (DBEF) sandwiched between a first and second image display. The display system is capable of multiple image functions.
Bistable Liquid Crystal Displays are described by Bryan-Brown et al. “Grating Aligned Bistable Nematic Device”, Proc SID XXVIII 5.3, pp 37-40 (1997) and U.S. Pat. No. 6,249,332 (Bryan-Brown et al.; 19 Jun. 2001) and U.S. Pat. No. 7,019,795 (Jones; 28 Mar. 2006). A bistable LCD has two energetically stable configurations of the liquid crystal molecules. Power is only required to switch from a first energetically stable state to the second energetically stable state. Consequently, a bistable LCD can be passively addressed with a first image, and power is only required to display a second image that is different from the first image. The bistable LC mode may be combined with optical components to enable a reflective bistable LCD. A reflective bistable LCD is particularly useful for viewing images in high ambient lighting conditions. A reflective bistable LCD is particularly useful for display applications requiring very low power consumption.